Measuring transducer

Abstract

The invention relates to a measuring transducer for charging stations of electric vehicles. In the measuring transducer, a measuring device is connected to a direct current charging circuit for detecting at least one direct current measurement variable. A transducer for converting the direct current measurement variable into an alternating current actuating variable is provided, and the measuring transducer also includes an actuating means for adjusting at least one alternating current variable in an alternating current measuring circuit as a function of the alternating current actuating variable.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS[0001]This patent application is a continuation of PCT Application No. PCT / EP2016 / 075758, filed Oct. 26, 2016, which claims priority to German Application No. 10 2016 103 556.4, filed Feb. 29, 2016, the entire teachings and disclosure of which are incorporated herein by reference thereto.FIELD[0002]The subject matter relates to a measuring transducer for charging stations of electric vehicles and to a method for operating a measuring transducer.BACKGROUND[0003]The increasing use of electric charging stations for electric vehicles is presenting new challenges with regard to the measurement technology to be employed. Particular technical challenges relate to the correct billing of electrical energy obtained. Apart from the charging of electric vehicles by means of alternating current, wide use is also made of charging with direct current. However, when charging by means of direct current, the problem arises that the measurement technology ...

AI Technical Summary

Benefits of technology

[0015]In particular, it is proposed that the direct current measurement variable is an electrical power. The electrical power is generally determined from the electrical voltage and the electrical current in the direct current charging circuit. If the direct current measurement variable is detected at short intervals, then the alternating current actuating variable can be tracked in likewise correspondingly small intervals. Here, the alternating current actuating variable is preferably an electrical power, in particular an electrical active power. In the alternating current measuring circuit, preferably only active power is used. This can be achieved in that in the alternating current measuring circuit parasitic, capacitive or inductive loads are minimised as far as possible and in the alternating current measuring circuit only an ohmic resistance is provided. According to the subject matter, the electrical active power is preferably lower by a factor than the electrical power in the direct current charging circuit. These factors are preferably 10, 100, 1,000, 5,000 or similar.

[0018]It is in particular possible to make available the current strength of the direct current charging circuit, determined on the basis of the voltage drop across the measuring resistor in a temperature-compensated manner. It is thus possible, to determine the direct current and the direct voltage in the direct current charging circuit independent of temperature in order to thus be able to determine the alternating current actuating variable independent of temperature.

[0023]The constant current source is preferably an adjustable resistor or has such an adjustable resistor. With the help of the adjustable resistor it is possible to adjust the current flow in the alternating current measuring circuit.

[0025]An active power of 46 W, for a factor of 1,000, as can be set in the transducer, can correspond to a direct current power in the direct current charging circuit of 46 KW. This means that if an electric vehicle charges at 46 KW, accordingly in the alternating current measuring circuit only 46 W of “measuring service” is used. A higher factor leads to an even lower use of “measuring service” in the alternating current measuring circuit, thereby increasing the efficiency of the measuring transducer.

Problems solved by technology

However, energy meters for direct current circuits are not produced on a large scale and are generally not authorised under the calibration regulations.

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